M.  L  NE^EL 


West  Virginia  University 
I.  C.  White  Library 

Illinois  no.  At 

COAL  MINING  INVESTIGATIONS 

COOPERATIVE  AGREEMENT 


State  Geological  Survey 

D^partm^nt  of  Mining  Engineering,  University  of  Illinois 

U.  S    Bureau  of  Mines 


BULLETIN  6 


Coal  Mining  Practice 


IN 


District  V 


BY 

S.   O.   ANDROS 


Urbana 

University  of  Illinois 

1914 


ilffiflM  i»i!!E  GEOLOGICAL  SURVEY 


3  3051  00006  3713 


1914 


-  3    L.  f--j 


3£L 


CONTENTS 


PAGE 

Introduction 7 

Description    of    coal    bed.. 9 

System    of    mining 12 

Ventilation   17 

Blasting 22 

Timbering  24 

Haulage 26 

Hoisting    31 

Preparation   of  ccal   32 


ILLUSTRATIONS 


PAGE 

1.  Map    showing   area    of    District    V Frontispiece 

2.  Igneous    dike    in    coal 10 

3.  Plan   of  mine  with   triple  main  entries 12 

4.  A   blow-through    in   a    narrow    pillar 13 

5.  Typical     roof -fall 15 

6.  Latch  in  rib  dug  to  receive  stopping 17 

7.  Mould    for    making    concrete-blocks    for    stoppings .■'  18 

8.  Explosion-door   in    concrete-block   stopping 19 

9.  A    method    of    placing    drill-holes    in    undercut    face 22 

10.  Shaft    bottom    with    steel    I-beam    roof    supports 24 

11.  Sketch  of  steel  room  supports 25 

12.  Plan   and   section    of   concrete-lined    shaft 27 

13.  Main    entry    and    wide    pit    car 28 

14.  Plan  of  shaft  bottom 32 

15.  Typical   surface  plant 33 


IE  BEL 


TABLES 

No.  PAGE 

1.  Comparative   statistics  for   District  V  and  the   State 8 

2.  Analyses    of    coal    in    beds    5    and    6 9 

3.  Pressure    developed    by    powdered    face   samples   in    explosibility   apparatus 11 

4.  Dimensions    of    workings    in    feet 14 

5.  Per   capita    production    of    coal 16 

6.  Causes   of  accidents   to   employees 20 

7.  Method  and  frequency  of  introduction  of  water 21 

8.  Ventilating  equipment  21 

9.  Blasting _  23 

10.  Timbering   _ 26 

11.  Haulage  equipment  29 

12.  Hoisting    31 

13.  Preparation  of  coal 33 

14.  Surface    equipment   34 


Fig.   1.     Map  showing  the  area   (shaded)   of  District   V. 


M.  L.  KE3l.L 


BULLETIN  OF 

ILLINOIS  COAL  MINING  INVESTIGATIONS 
COOPERATIVE  AGREEMENT 

Issued  bi-monthly 
VOL.  I  No.  3 

COAL  MINING  PRACTICE  IN  DISTRICT  V 

By  S.   O.   ANDROS 


INTRODUCTION 

District  V  of  the  Illinois  Coal  Mining  Investigations,  as 
shown  in  fig.  1,  comprises  those  mines  working  in  Saline  and 
Gallatin  counties  in  bed  5  of  the  Illinois  Geological  Survey  cor- 
relation. A  detailed  description  of  the  districts  into  which  the 
State  has  been  divided  and  the  method  of  collecting  the  data 
upon  which  this  bulletin  is  based  is  contained  in  Bulletin  I, 
"A  Preliminary  Report  on  Organisation  and  Method." 

Seven  typical  mines  were  examined  in  this  District  in 
which  there  are  33  mines,  21  shipping  and  12  local.  The  total 
production  of  the  district  for  the  year  ended  June  30,  1912, 
was  4,151,702  tons  or  7.2  per  cent  of  the  total  production  of 
the  State  during  the  year.  The  coal  mined  by  machines  in 
District  V  totaled  3,753,319  tons,  90.2  per  cent  of  the  total 
production  of  the  district.  A  direct  result  of  undercutting 
such  a  large  percentage  is  the  use  of  less  powder.  The  pro- 
duction of  the  district  is  7.2  per  cent  of  the  coal  output  of  the 
State.  For  the  year  ended  June  30,  1912,  only  53,154  kegs  of 
powder,  4.2  per  cent  of  the  powder  used  in  the  State,  were 
used  in  the  district.  There  were  78.1  tons  of  coal  gained  for 
each  keg  of  powder  used. 

In  the  mines  of  this  district  there  were  employed  an  average 
of  4,822  men  for  an  average  of  170  days,  making  a  total  of 
819,740  days'  work  performed  during  the  year,  or  6.5  per  cent 
of  the  total  days  of  work  in  coal  mines  throughout  the  State. 

Table  1  gives  comparative  statistics  for  the  district  and 
for  the  State  in  1912. 

The  operators  of  the  district  offered  every  facility  for  study 
of  the  mines,   and  the  superintendents    and    mine    managers 


8 


COAL  MINING  INVESTIGATIONS 


freely  supplied  all  information  requested.     Special  acknowl- 
edgments are  due  to  Mr.  William  Johnson,  General  Superin- 

Table  1. — Comparative  statistics  for  District  V  and  the  State 
for  the  year  ended  June  SO,  1912* 


Total  production  

Tons   mined   by   machine 

Average  daily  tonnage  

Average  days  of  active  operation 

Total  employees  

Days  of  work  performed  

Surface  employees  

Underground  employees  

Average  number  of  face  workersb 

(miners,  loaders,  and  machine  men) 

Underground  employees  per  each  surface  em- 
ployee   

Tons  mined  per  day  per  employee 

Tons  mined  per  day  per  surface  employee 

Tons    mined   per   day   per   underground   em- 
ployee   

Tons  per  face  worker  per  dayb 

Fatal   accidents  

Per  cent  from  falling  coal  or  rock 

Per  cent  from  pit  cars   

Per  cent  from  gas  explosions  

Per  cent  from  explosives  

Deaths  per  1,000  employees  

Tons  mined  to  each  life  lost 

Non-fatal  accidents  

Per  cent  from  falling  coal  or  rock 

Per  cent  from  pit  cars   

Per  cent  from  gas  explosions  

Per  cent  from  explosives   

Per  cent  from  undercutting  machines  

Non-fatal  accidents  per  iooo  employees 

Tons  mined  to  each  non-fatal  accident 


District 


4,151,702 

3,753,319 

24,484 

170 

4,822 

819,740 

414 

4,408 

2,728 

10.6 

5-i 
59-2 

5-6 

8.1 

28 

42.9 

10.7 

32.1 

7-i 

5-8 

148,275 

65 

43-2 

18.5 

9.2 

4-6 

9.2 

134 

63,872 


State 


57,514,240 

25,550,oi9 

359,464 

160 

79,4H 

12,705,760 

7,049 

72,362 

53,3i8 

10.3 

4-5 

50.9 

4-9 
6.7 
180 

54-4 
18.8 

6-9 
7.2 

2.3 

319,524 

800 

45-5 

26.3 

2.9 

2.6 

2.8 

10.1 

71,893 


Per  cent 

of 
District 


7.2 

14.7 
6.8 


6.1 
6.5 
5-9 
6.1 

5-i 


15.5 


aC6mpiled  from  Thirty  First  Annual  Coal  Report  of  Illinois. 
bShipping  mines  only. 


tendent  of  the  Saline  County  Coal  Company,  and  to  Mr.  Hugh 
Murray,  President  of  the  Gallatin  Coal  and  Coke  Company, 
for  their  valuable  assistance  and  advice. 


DESCRIPTION  OP  COAL  BED 


DESCRIPTION  OF  COAL  BED 


Bed  5  in  Saline  and  Gallatin  counties  lies  at  a  depth  of 
25  to  450  feet,  being  nearer  the  surface  along  the  southern  por- 
tion. The  bed  varies  in  thickness  from  4  to  8  feet,  averaging 
5}$  feet  in  Saline  County  and  4  feet  in  Gallatin  County.  The 
coal  of  bed  5  has  a  bright  luster  and  is  harder  than  No.  6  coal. 
Table  2  gives  the  proximate  analysis  and  unit  coal  B.  t.  u. 
for  coal  of  bed  6  in  Perry,  Jackson,  Franklin  and  Williamson 
counties  or  District  VI  and  coal  of  bed  5  in  District  V.  No.  5 
coal  in  this  district  has  more  sulphur,  less  moisture,  and  a 
slightly  higher  calorific  value  than  No.  6  coal  in  District  VI. 

Table  2. — Analyses  of  coal  in  beds  5  and  6. 


Proximate  analysis  of  coal 

ist;     "As     ree'd"     with     total 

3 

<u 

moisture 

+-* 

-o 

•4-1 

u 
u 

s 

W 

6 

2nd;    "Dry"    or    moisture    free 

C/3 

3 
PQ 

S3 

PQ 

CO 

O 

2 

>  6 

15  2 
*8 

en 

O 
O 

*5 
P 

5 

V 

27- 

6-75 

3549 

48.72 

9.04 

2.92 

12276 

Dry 

38.06 

52.25 

9.69 

3-13 

13165 

14812 

6 

VI 

58 

9.21 

34.00 

48.14 

8.71 

1-53 

1 1825 

Dry 

3745 

53-02 

9-59 

1.68 

13025 

14583 

Tlie  bed  does  not  contain  the  numerous  bands  which  char- 
acterize the  No.  6  coal  both  to  the  west  and  cast  of  the  Du 
Quoin  anticline.  In  some  mines  a  blue  band  is  developed  lo- 
cally, in  general  where  the  seam  is  thickest.  In  places  a  hard 
calcareous  shale  band  may  be  seen.  It  is  much  harder  than 
the  blue  band  and  where  developed  is  usually  from  two  to 
three  feet  above  the  floor,  as  compared  with  nine  to  eighteen 
inches  for  the  blue  band. 

The  mines  in  this  district  are  more  gassy  than  those  in 
No.  6  coal  west  of  the  Du  Quoin  anticline  possibly  because  the 
impermeable  shale  overlying  the  bed  has  prevented  the  escape 
of  gas.  They  are  not  so  gassy,  however,  as  mines  in  No.  f>  east 
of  the  anticline. 


10 


COAL  MINING  INVESTIGATIONS 


The  roof  of  No.  5  in  this  district  is  a  shale  varying  in 
color  from  light  gray  to  black,  and  locally  may  be  laminated 
and  interbedded  with  bone  and  stringers  of  coal  for  a  distance 
of  3  feet  above  the  seam.  The  roof  usually  contains  also  many 
concretions  of  iron  pyrites  called  "nigger-heads."  These  have 
more  cohesion  with  the  rest  of  the  roof  material  than  do  the 
nigger-heads  in  the  Danville  district. 


Fig.    2.      Igneous   dike    in    coal. 


The  floor  is  fireclay  which  in  places  contains  much  sand 
and  heaves  badly  when  wet.  The  bed  does  not  lie  as  flat  as 
the  unfaulted  No.  6,  but  contains  many  hills  and  rolls  causing 
grades  as  high  as  15  per  cent  in  the  entries  of  some  mines. 
The  coal  is  not  pinched'  out  at  these  hills,  but  follows  their 
contours  with  undiminisljetl  thickness. 

The  district  is- characterized  by  the  presence  of  an  igneous 
intrusion  identified  by  Albert  Johansen,  formerly  of  the  U.  S. 
Geological  Survey,  as  mica-peridotite.  This  dike  in  some  places 
penetrates  and  has  its  apex  in  the  coal,  as  shown  in  fig.  2;  in 
others  it  extends  on  through  the  bed  into  the  overlying  strata. 
The  dike  varies  in  thickness  at  the  coal  horizon  from  a  few 
inches  to  many  feet,  and  can  be  traced  lineally  for  several 
miles.  Considerable  gas  and  water  are  generally  found  in  the 
vicinity  of  the  intrusion. 

The  coal-dust  of  this  district  when  air-dried  and  tested  in 


DESCRIPTION  OF  COAL  BED 


11 


the  laboratory  at  Urbana  shows  moderate  explosibility.  Com- 
parison of  the  average  pressure  developed  by  this  dust  when 
tested  in  the  explosibility  apparatus  with  the  pressures  devel- 
oped by  the  dusts  of  other  districts,  is  given  in  Table  3. 

Table  3. — Pressure  developed  by  powdered  face  samples  in  ex- 
p losibility  appa  ratu s 


District 

No. 

samples 

Pressure  in  pounds  per 
square  inch  at  2i92°F 

I 

ii 

8.400 

II 

5 

5.880 

III 

5 

/.805 

IV 

17 

7-700 

V 

7 

7-105 

VI 

16 

5-950 

VII 

24 

7-175 

VIII 

6 

8.925 

12 


COAL   MINING  INVESTIGATIONS 


SYSTEM   OF  MINING 


In  the  30  mines  of  Saline  County  there  are  no  slopes  or 
drifts,  all  of  the  coal  being  hoisted  entirely  through  shafts; 
but  in  Gallatin  County  the  coal  is  reached  by  5  slopes,  2 
drifts,  and  3  shafts.  Stripping  the  overburden  from  the  seam 
is  not  done  in  either  county. 


Fig.   3.      Plan   of   mine   with  triple  main   entries. 


The  output  of  the  average  mine  in  Gallatin  County  is 
small.  The  largest  mine  produced  in  the  year  ended  June  30, 
1912,  only  28,439  tons  as  compared  with  523,583  tons  for  the 


MINING  PRACTICE 


13 


largest  mine  in  Saline  County.  The  method  of  mining  the  bed 
is  the  same  in  both  counties.  The  room-and-pillar  system  is 
used  exclusively  in  the  district.  A  main  haulage  entry  and 
parallel  air-course  were  driven  in  every  mine  except  one.  In 
it  triple  main  entries  were  driven,  two  for  intake  air  and  one 
for  return  air  and  haulage,  as  shown  in  fig.  3. 

In  the  smaller  mines  and  in  many  of  the  larger  ones  of 
the  district  the  dimensions  of  workings  are  unsuitable  to  the 
roof  conditions.  The  main  entries  vary  in  width  from  14  to 
16  feet.  A  few  shaft  pillars  have  been  gouged.  Gouging  the 
room  pillars  often  results  in  a  blow-through,  as  shown  in  fig.  4. 


Fig.  4.     A  blow-through   in  a  narrow  pillar. 


The  width  of  the  room  in  the  foreground  is  26  feet  ;  that  of 
the  room  in  which  the  men  are  standing,  22  feet.  The  width 
of  room-pillar  is  !)  feet.  Room-stumps  left  when  rooms  are 
turned  off  the  cross  entries  generally  are  small.  The  closing 
of  entries  by  roof  falls  may  often  be  attributed  to  local  squeezes 
which  ride  over  the  room-stumps.  Table  4  gives  dimensions  of 
workings  for  each  mine  visited. 

The  custom  of  driving  wide1  rooms  and  entries,  of  Leaving 
narrow  pillars  throughout  the  mine,  and  of  obtaining  all  the 
coal  possible  on  the  advance  working  without  attempting  to 
draw  pillars,  has  resulted  in  a  percentage  of  extraction  of  the 
seam  which  is  high  for  Illinois  mines.     The  percentages  given 


14 


COAL  MINING  INVESTIGATIONS 


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MINING  PRACTICE 


15 


in  Table  5  were  calculated  from  measurements  made  in  the 
mine  and  checked  by  figures  of  tons  per  acre  obtained  from  the 
books  of  the  operating  companies.  The  extraction,  averaging 
67.1  per  cent  for  the  7  mines  examined,  was  accomplished  only 
with  greatly  increased  expense  for  cleaning  up.  The  cost  of 
coal  at  the  pit  mouth  in  this  district  would  be  much  lower  if 
entries  and  rooms  were  driven  narrower  leaving  wide  pillars 
to  be  pulled  on  return  working.  The  heavy  roof  falls  con- 
stantly occurring  in  workings  with  the  present  dimensions 
would  be  avoided  and  the  haulage  ways  would  be  kept  free  from 
gob.  Fig.  5  shows  a  typical  roof  fall,  which  closed  a  room 
that  had  been  driven  up  only  75  feet. 


Fig.   5. 


Typical   roof-fall. 


The  shale  of  the  immediate  roof  is  weak,  often  containing 
coal  fingers,  and  breaks  quickly  when  unsupported  in  wide 
spans.  The  roof  shale  is  drawn  when  it  shows  a  strongly  de- 
veloped parting  not  over  4  inches  above  the  coal;  but  such  a 
parting  rarely  occurs,  and  the  coal  bed  is  so  thin  that  top  coal 
cannot  profitably  be  left  in  place.  Consequently  when  sub- 
jected to  changes  of  temperature  and  humidity  in  the  air  cur- 
rent the  immediate  roof  spalls  badly;  and  as  timber  is  used 
sparingly  in  this  district  both  the  danger  of  accidents  and  the 
clean-up  expense  are  increased.  In  some  mines  about  9  inches 
of  bottom  coal  is  left  below  the  blue  band,  but  as  this  bottom 


16 


COAL   MINING  INVESTIGATIONS 


coal  is  not  of  good  quality  increased  facility  in  shooting  recom- 
penses for  the  loss  of  the  coal. 

The  igneous  dike  in  the  district  has  not  caused  a  modifi- 
cation of  the  system  of  mining,  although  it  has  added  locally 
to  the  expense  because  of  the  greatly  increased  cost  of  driving 
through  hard  rock. 

The  laborers  are  of  various  nationalities,  with  Americans 
possibly  predominating.  Others  are  English,  Scotch,  German, 
Lithuanian,  Hungarian,  and  (Russian.  The  production  per 
capita  in  the  district  is  higher  than  the  average  for  the  other 
districts  combined;  5.1  tons  of  coal  per  day  being  produced  per 


Table  5 

.—Per 

capita  production 

of  coal 

0 

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<u 
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CD 

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CD    <u 

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H 

H  S 

O     D 

H 

w 

H^ 

43 

2500 

415 

30 

385 

260 

12.8 

6.0 

83.3 

6-5 

9-6 

44 

1400 

286 

32 

254 

184 

8.0 

4-9 

43-7 

5-5 

7-6 

45 

I6O0 

258 

16 

242 

198 

15.1 

6.2 

100.0 

6.6 

8.1 

46 

I IOO 

239 

14 

225 

163 

16.0 

4-6 

78.6 

4-9 

6-7 

47 

400 

50 

6 

44 

40 

7-3 

8.0 

66.6 

9.1 

TO.O 

48 

800 

182 

17 

165 

92 

9-7 

4-4 

47.1 

4.9 

74 

49 

I  IOO 

213 

13 

200 

125 

15-4 

5-2 

84.6 

5-5 

8.8 

Dis- 

trict Va 

24484 

4822 

414 

4408 

2728b 

10.8 

5-i 

58.6 

5-5 

8.1* 

All 

other 

dis- 

tricts 

com- 

bined 

334980 

74589 

6635 

67954 

50590 

10.3 

4-5 

50.5 

4.9 

6.0* 

a  Year    ended   June    30, 
b  Shipping  mines  only. 


1912. 


employee  as  compared  with  4.5  tons  per  day  for  all  other  dis- 
tricts combined.  The  tonnage  per  day  per  face  worker  is  8.1 
for  the  district  and  6.0  for  all  other  districts.  The  large 
amount  of  coal  mined  by  machines  in  District  V  accounts  for 
this  high  individual  production.  Table  5  gives  the  per  capita 
production  of  coal  at  each  mine  examined. 


MINING  PRACTICE 


17 


VENTILATION 
Considerable  marsh-gas  is  generated  in  bed  5  but  the  en- 
tries are  driven  ahead  of  the  rooms  in  the  development  of  the 
mines  and  drain  the  bed  so  that  usually  in  rooms  there  is  not 
much  gas,  although  an  amount  sufficient  to  cause  as  many  as 
4  or  5  fires  per  shift  after  shots  in  the  rooms  may  be  left  in- 
cluded in  the  coal.  In  this  district  many  of  the  explosions 
which  have  occurred  with  attendant  loss  of  life  could  have  been 
prevented  by  a  more  careful  inspection  of  the  working  places 
before  the  men  were  allowed  to  enter  them.  An  especially 
careful  examination  should  be  made  of  connections  between 
old  and  active  workings;  also  of  the  faces  of  entries  driven  in 
advance  of  the  rooms,  as  these  faces  serve  as  the  outlet  for  the 
gas  drained  from  the  bed. 


Fig.   6.     Latch  in   rib  dug  to  receive  stopping. 


The  comparatively  small  quantities  of  gas  in  the  rooms 
has  given  rise  to  the  belief  that  strong  ventilation  is  not  neces- 
sary, and  as  a  consequence  the  quantity  of  air  supplied  to  the 
mines  is  generally  not  adequate.  The  volume  of  air  is  small 
in  this  district  in  proportion  to  the  area  to  be  ventilated.  In 
many  mines  the  insufficient  quantity  supplied  by  the  fan  at 
the  air-shaft  is  decreased  still  more  by  loss  through  leaky  stop- 
pings during  the  passage  of  the  current  through  the  entries. 

One  mine  operates  with  proper  consideration  of  the  dan- 


18 


COAL   MINING  INVESTIGATIONS 


ger  in  a  combination  of  gas  and  explosive  dust.  Ventilation  is 
ample,  the  fan  delivering  an  average  of  200,000  cubic  feet  per 
minute.  This  volume  is  subject  to  little  leakage  in  the  entries, 
the  stoppings  being  efficient.  Stoppings  are  built  of  hollow 
concrete  blocks  set  into  the  rib,  roof,  and  floor  sufficiently  deep 
to  provide  a  good  joint.  The  cut  is  made  about  2  inches  wider 
than  the  bearing  side  of  the  blocks,  and  the  joint  in  rib,  roof, 
and  floor  is  packed  with  cement  mortar  with  the  proportions, 
1,  Portland  cement;  3,  sharp  washed  sand.  The  rib  cut,  as 
shown  in  fig.  6,  is  14  inches  deep.  The  concrete  blocks  are 
made  on  the  surface  in  a  mould  as  shown  in  fig.  7.     The  con- 


Fig.    7.      Mould    for    making   concrete-blocks    for    stoppings. 


crete  used  for  the  blocks  has  the  proportions:  1,  Portland 
cement;  2,  sharp  washed  sand;  4,  crushed  limestone.  Each 
block  weighs  180  pounds,  and  has  outside  dimensions  of  8  by 
12  by  24  inches.  The  cost  of  material  is  14  cents  per  block; 
labor,  8  cents;  total  cost  at  pit  mouth,  22  cents.  Two  men 
build  in  one  day  a  stopping  7  by  10  feet,  preparing  the  cuts  in 
the  rib  and  roof  and  the  trench  in  the  floor  to  receive  the 
blocks,  at  a  total  labor  cost  of  $7.25,  or  10.4  cents  per  square 
foot.  The  cost  of  material  was  10.6  cents  per  square  foot  (53 
blocks).  With  a  cost  of  eight-tenths  of  a  cent  per  block  for 
transportation  from  the  surface  to  the  location  in  the  mine, 
the  cost  of  transportation  per  square  foot  of  stopping  was  six- 


MINING  PRACTICE 


19 


tenths  of  a  cent.  The  total  cost  of  a  laid  stopping,  therefore, 
was  21.6  cents  per  square  foot.  Provision  is  made  at  this  mine 
for  the  expansion  of  an  explosion  wave,  the  idea  being  to  pre- 
vent the  propagation  through  the  main  entries  of  a  local  explo- 
sion in  a  room  or  entry.  An  explosion  door  (fig.  8)  is  built 
into  every  eighth  stopping  along  the  main  entries.  This  door 
is  built  of  two  thicknesses  of  one  inch  shiplap  boards,  and 
swings  vertically  on  a  one-inch  iron  rod.  Uprights  and  cas- 
ings are  built  into  the  stopping.  The  width  of  the  door,  4  feet 
3  inches,  is  the  same  whatever  the  width  of  the  crosscut,  but 
the  height  varies  with  the  stopping. 


Fig.   8.      Explosion-door  in   concrete-block  stopping. 


The  air-shafts  have  two  compartments,  one  for  ventilation 
and  one  for  an  escapeway.  One  mine  has  an  exception  to  the 
usual  small  escapeway  compartment,  the  escapement  being  4% 
by  11  feet  in  the  clear.  The  stairway  is  24  inches  wide  with 
steel  treads  spaced  on  12-inch  centers.  Platforms  at  landings 
are  broad,  and  ascent  through  this  escapeway  is  easy.  As  the 
air-shaft  is  of  concrete  construction  the  partition  between  es- 
capement and  air  compartment  does  not  leak,  and  there  is  no 
short  circuiting  of  the  intake  current  through  the  partition. 

For  the  year  ended  June  30,  1912,  the  coal  output  of  the 
district  amounted  to  7.2  per  cent  of  the  State;  but  15.5  per 
cent  of  the  fatal  accidents  in  Illinois  that  vear  occurred  in  this 


20 


COAL  MINING  INVESTIGATIONS 


district.  The  record  for  the  year  ended  June  30,  1911,  shows 
that  although  6.5  per  cent  of  the  production  of  the  State  was 
mined  in  this  district,  10.2  per  cent  of  the  fatal  accidents  also 
occurred  there.  An  analysis  of  the  causes  of  accidents  com- 
pared in  Table  6  for  District  V  and  for  all  other  districts  com- 
bined shows  the  necessity  for  better  ventilating  equipment. 
The  installation  of  adequate  fans  and  the  employment  of  suffi- 
cient face  bosses  would  reduce  the  number  of  accidents. 


Table  6. — Causes  of  accidents  to 

employees 

1 

Cause 

Per  cent    of 

fatal  accidents 

Per  cent    of 
non-fatal  accidents 

District  V 

42.9 
10.7 
32.1 

7-1 
0.0 

All  other 

districts 

combined 

District  V 

All  other 

districts 

combined 

Falling  coal  or  rock 

Pit  cars  

56.5 
20.4 

1-3 

7-3 
0.0 

43-2 

18.5 

9.2 

4-6 

9.2 

45-8 
27.0 

Gas   and   dust   explosions 

Use  of  explosives  

Undercutting    machines.... 

2.3 
2.4 
2  2 

1Compiled  from  the  Thirty-first  Annual  Coal   Report  of  Illinois. 


In  spite  of  frequent  local  explosions  and  the  presence  of 
much  dry  explosible  dust,  humidification  of  mine  air  in  winter 
has  not  been  considered  necessary  by  the  local  operators  on 
account  of  the  naturally  high  relative  humidity.  The  relative 
humidity  of  the  working  places  in  summer  varies  from  90  to  95 
per  cent.  The  average  of  the  return  air  in  summer  is  98  per 
cent;  in  winter,  96.  The  introduction  of  water  into  the  mine  is 
for  laying  the  dust  on  the  roads;  the  increase  in  humidity  by 
this  means  being  very  slight.  At  6  of  the  mines  examined 
sprinkling  is  done  with  a  car.  In  one  mine  sprinkling  with 
hose  is  done  each  night  in  winter;  in  another,  calcium  chloride 
is  put  on  the  floor  of  entries  where  the  dust  is  thick.  Calcium 
chloride  being  a  hygroscopic  salt  absorbs  moisture.  Coal  dust 
when  covered  with  it  becomes  moistened  and  remains  damp  as 
long  as  the  calcium  chloride  continues  to  absorb  moisture.  The 
finest  coal  dust  is  thus  prevented  from  being  thrown  into  sus- 
pension in  the  air-current  by  the  passage  of  trips  and  by  the 
feet  of  men  and  animals.  At  this  mine  it  was  found  that  by 
using  1%  pounds  of  granulated  calcium  chloride  per  square 
yard  of  floor,  fine  coal  dust  lying  one  inch  thick  was  kept  moist 
for  six  months.     The  use  of  this  salt  has  been  so  satisfactory 


MINING  PRACTICE 


21 


at  this  mine  that  a  much  greater  floor  area  will  be  covered  in 
the  future.  In  the  small  quantity  bought  for  experimentation 
calcium  chloride  cost  $13  per  ton.  This  cost  will  be  consider- 
ably less  if  the  salt  is  bought  in  large  quantity.  Table  7  gives 
the  method  and  frequency  of  introduction  of  water  at  each 
mine  examined. 


Table  7. — Method  and  frequency  of  introduction  of  water 


No.  mine 


43- 
44- 
45- 

46.. 

47- 
48. 
49- 


Method 


Sprinkling  from  car 
Sprinkling  from  car 
Sprinkling  from  car 
Sprinkling  from  car 


Sprinkling  from  hose 


Frequency 


Weekly 

Weekly 

Irregular 

Three  times  per  week  s  \? 


,-V 


Daily  in  winter       \^ 


^ 


V 


In  only  a  few  mines  in  the  district  is  proper  precaution 
against  underground  fires  in  the  shaft  pillar  observed.  Mules 
are  usually  stabled  below,  and  hay  is  often  taken  down  in  open 
cars  and  sometimes  is  allowed  to  lie  for  several  hours  on  the 
stable  floor  after  unloading.  Extreme  carelessness  is  tolerated 
in  the  use  of  naked  lights  in  underground  stables ;  enforcement 
of  the  provision  of  the  State  mining  law  prohibiting  their  use 
in  stables  being  observed  in  but  few  mines. 

Table  8  gives  for  each  mine  examined  da  (a  about  venti- 
lating equipment. 


Table  8. — Ventilating  equipment 


rt 

O     0-1 
U  M-l 

C 

M-l 

0 

O 

tJ.c 

.2     ° 

.5  ? 

ex 

(L>.~ 

rt   c 

•0  •- 

a   & 

N 

-'i 

V5   « 

hJ     rt 

Q 

CO 

H 

Q«~ 

£ 

<^< 

43 

160 

8  by  8 

Clifford-capell 

13 

5/2 

Timber 

Timber 

44 

270 

11  by  20 

Paddle-wheel 

20 

6 

Brick 

Concrete 

45 

320 

6  by  8 

Paddle-wheel 

12 

5 

Corrugated  iron 

Timber 

46 

450 

8  by  12 

Paddle-wheel 

20 

5 

Corrugated  iron 

'limber 

47 

100 

6  by  6 

Paddle-wheel 

IO 

3 

Timber 

Timber 

48 

76V2 

5  by  10 

Paddle-wheel 

18 

4 

Timber 

Timber 

49 

337 

6  by  10 

Paddle-wheel 

14 

4 

Corrugated  iron 

Timber 

^'Paddle-wheel"    refers   to   straight   blade   type   of   fan. 


22 


COAL   MINING  INVESTIGATIONS 


BLASTING 

In  District  V  a  great  proportion  of  the  coal  mined  is  under- 
cut by  machines.  During  the  year  ended  June  30,  1912,  there 
were  produced  in  the  district  4,151,702  tons  of  which  3,753,319 
tons,  or  90.2  per  cent  of  the  total  output  of  the  district,  were 
mined  by  machines.  In  five  of  the  mines  examined  electric 
chain  undercutting  machines  were  used;  shooting  off  the  solid 
was  done  in  two  mines;  and  in  one  mine  shooting  off  the  solid 
was  done  in  one  section  and  undercutting  in  another.  In  those 
mines  where  the  coal  is  undercut  before  shooting,  it  is  usually 
snubbed  by  hand,  increasing  the  height  of  undercutting  from 
15  to  21  inches  above  the  floor.  This  hand-snubbing  not  only 
makes  a  greater  percentage  of  lump  coal,  but  also  makes  pos- 
sible smaller  charges  of  powder.  The  output  of  coal  per  un- 
dercutting machine  varies  from  112  to  200  tons  a  shift  at  the 
mines  examined.  The  number  of  tons  of  coal  gained  per  25- 
pound  keg  of  powder  is  high  for  the  district  as  a  whole,  aver- 
aging 78.1  for  the  year  ended  June  30,  1912.  This  high  average 
was  made  possible  by  the  performance  at  the  undercutting 
mines  where  the  number  of  tons  per  keg  varied  from  108  to  125. 
The  solid  shooting  mines  make  a  poor  gain  of  coal  in  blasting, 
obtaining  only  18  to  25  tons  per  keg. 


■6i     V-0 
Hai 


Hand  Snubbing  ^ 


t m 

Machine  Cut  T^M^B 


ir18 

■id- 


J_£I 


FRONT 


SIDE 


Fig.   9.     A  method   of   placing  drill-holes  in  undercut   face. 


The  district  uses  black  powder  exclusively,  but  could  op- 


MINING  PRACTICE 


23 


erate  with  fewer  explosions  and  fewer  fires  after  shots  if  per- 
missible explosives  were  used.  In  three  of  the  seven  mines 
inspected,  unnecessarily  fine  powder  was  used,  thereby  increas- 
ing the  amount  of  slack. 

Dangerous  blasting  practice  exists  in  some  of  the  smaller 
mines  where  shooting  is  done  off  the  solid  and  drill  holes  2V2 
inches  in  diajmeter  are  8  feet  long  in  a  seam  5%  feet  thick. 
Excessive  charges  of  powder  are  loaded  and  "bug-dust"  tamp- 
ing is  common.  The  explosibility  of  the  dust  in  this  district 
should  make  obvious  to  the  miners  the  danger  in  present  blast- 
ing methods  and  they  should  be  the  first  to  insist  on  observance 
of  the  State  law.  The  laws  now  existing  in  Illinois  are  suffi- 
cient to  protect  the  miners  from  nearly  all  preventable  acci- 
dents, but  the  enforcement  of  these  laws  is  very  lax.  In  three 
of  the  seven  mines  examined  short-firers  are  employed,  but 
they  ordinarily  do  not  refuse  to  fire  shots  tamped  with  bug 
dust.  In  only  one  mine  is  clay  used  for  tamping.  In  those 
districts  where  shot-firers  refuse  to  fire  charges  not  tamped 
with  clay  the  miners  soon  learn  to  use  clay  only. 

The  powder  is  transported  from  the  surface  to  the  entries 
in  open  pit  cars,  as  is  the  custom  throughout  the  State.  Pow- 
der is  bought  in  steel  kegs;  the  paper  powder  keg  not  being 
used.  The  usual  square  hole  made  by  a  pick  point  was  noticed 
in  the  heads  of  many  kegs.  The  practice  of  opening  them  with 
pick  points  is,  however,  no  more  prevalent  in  this  district  than 
it  is  in  other  parts  of  Illinois. 

Table  9. — Blast  in  (j 


6 

•So 

C 

rt 

a  bo 

.SP  « 
'53 

•O.S 

_  0 

«/>  E 
c 

O   u 
(— 1   v 

O  <u 

■8  ° 

in  c- 

bfi  0 

«-M 
O 

Si  <« 
rt 

5 

>> 

0 

Tons   of   coal 

per  keg  of 

powder 

Per  cent  of 
lump    over 
154  inches 

43 

Undercut 

24 

112 

F 

5 

2J/2 

Squib 

108 

70 

44 

Undercut 

18 

2O0 

FF 

6 

1/2 

Squib 

125 

70 

45 

Undercut 

15 

150 

FF 

5 

2 

Squib 

116 

46 

Shot  off 

F 

solid 

18 

C 

5K2 

2% 

Fuse 

100 

3  inches 

47 

Shot  off 

solid 

None 

F 

6,8 

1% 

Fuse 

22y2 

55 

48 

Undercut 

18 

112 

FF 

5/2 

1% 

Fuse 

ro7 

70 

49 

Shot  off 

F 

solid 

None 

C 

8 

2/2 

Fuse 

18 

75 

24 


COAL   MINING  INVESTIGATIONS 


Table  9  gives  data  covering  blasting  practice  in  the  dis- 
trict. The  figures  for  percent  of  lump  coal  over  1%  inches 
were  obtained  from  the  books  of  the  company  in  each  case. 

Fig.  9  shows  a  typical  method  of  placing  holes  in  an 
undercut  face  where  no  rock-band  is  present. 

TIMBERING. 

This  district  is  characterized  by  insufficient  timbering  in 
entries.  The  roof  spalls  badly  on  exposure  to  air,  especially  in 
those  sections  where  the  draw-slate  has  not  been  pulled  down. 
The  district  would  profit  financially  and  the  number  of  acci- 
dents would  be  decreased  if  the  timbering  expenditure  were 
doubled.  It  is  a  false  economy  which  prohibits  the  purchase 
of  necessary  timber  in  a  coal  mine,  because  the  money  appar- 


-^ 

m  _  ''V'~T*|S     ■■fejji 

Fig.   10.     Shaft  bottom  with  steel  I-beam  roof  supports. 


ently  saved  is  lost  twice  over  in  added  expense  of  cleaning-up 
and  hauling.  The  total  timbering  cost  for  the  mines  examined 
varies  from  1  to  2  cents  per  ton  of  coal  mined,  and  averages 
1.5  cents.  Hundreds  of  feet  of  entry  with  bad  roof  are  sup- 
ported by  props  alone;  sets  are  seldom  used  at  any  of  the 
mines  examined.  The  quality  of  timber  is  poor,  and  the  three- 
piece  gangway  set  when  used  is  generally  constructed  of  split 
room-props  of  small  diameter. 


MINING  PRACTICE 


25 


In  rooms  the  number  of  props  is  inadequate  for  safe  roof 
support,  and  the  miners  are  not  compelled  to  keep  their  props 
close  to  the  face.  In  many  rooms  examined  the  last  prop  in 
place  under  bad  roof  was  20  feet  from  the  face.  The  number 
of  accidents  from  fall  of  roof  can  be  decreased  in  this  district 
if  proper  supervision  is  exercised  over  the  working  place  of  the 
miner.  To  obtain  this  supervision  it  is  necessary  to  have  nu- 
merous face  bosses.  The  operators  should  furnish  a  plentiful 
supply  of  good  props,  and  pull  them  after  a  room  is  driven  up. 


The  room-props  in  this  district  are  of  poor  quality,  less 
than  one  per  cent  being  white  oak.  In  some  mines  of  the  dis- 
trict room-props  measure  only  21-.  indies  in  diameter  at  the 
small  tip.  Table  10  gives  data  on  timbering.  The  figures  for 
the  number  of  props  per  100  square  feet  of  roof  were  obtained 
by  counting  the  props  in  a  measured  length  in  each  of  several 
typical  rooms  of  known  width.  The  average  number  of  props 
per  100  square  feel  of  roof  is  3.3  for  this  district  as  compared 
with  an  average  of  5.5  per  100  square  feet  of  roof  for  the  Dan- 
ville district,  which  has  a  similar  roof. 

The  shaft  bottoms  of  all  except  one  of  the  mines  examined 
are  crudely  timbered.  The  exception  has  a  modern  bottom 
permanently  timbered  with  steel,  as  shown  in  fig.  10.  One  end 
of  the  12-inch  I-beam  is  set  in  a  hitch  in  the  rib  and  the  other 
end  rests  on  a  15-inch  I-beam  stringer  as  shown  in  tig.  11. 
The    stringers    are    supported     by    12-inch    steel   I-beam     legs 


26 


COAL  MINING  INVESTIGATIONS 


which  are  riveted  with  angle-iron  to  a  7-inch  by  14-inch  steel 
plate  %-inch  thick.  Both  the  hoisting  and  air  sharts  of  this  mine 
are  fire-proof,  and  are  the  only  concrete  lined  shafts  in  the  dis- 
trict. Both  shafts  are  concreted  through  50  feet  of  top  soil  and 
for  a  further  distance  of  20  feet  in  the  sandstone.  Fig.  12  shows 
the  plan  and  vertical  section  of  the  hoisting  shaft.  Excavation 
through  the  top  soil  and  sandstone  was  made,  and  the  lining 


Table  10. — Timbering 


1/5     C 

Room  Props 

W5     w" 

6 

Total  timber 
in  cents  per 
of  coal  min 

3     J- 

II 

0  <u 
Q  * 

No.   per    100 

square  feet 

of   roof 

Cost  in  cents 

per  100  squan 

feet  of  roof 

Diameter  of 

small  tip  in 

inches 

"5  Id 

C     t/5 

^  0 

u 

0 

S  <^ 

P     C/5 
O 

43 

1/2 

No 

5-7 

5i-3 

2l/2  to  4 

8,  10 

24 

Both 

44 

1 

Yes 

2-5 

20.0 

4 

8 

18 

Both 

45 

Yes 

1.6 

9.2 

4 

534 

24 

Both 

46 

No 

2.4 

12.0 

4 

5 

24 

Split 

47 

1 

No 

2.3 

20.7 

4 

6 

18 

Both 

48 

2 

No 

2.7 

16.5 

4 

5,6,8 

18 

Both 

49 

m 

No 

5-1 

30.6 

2*/2  to  4 

6 

8 

Both 

was  built  up  from  the  bottom  beginning  with  the  water  seal 
at  solid  rock.  The  concrete  is  reinforced  vertically  with  %- 
inch  by  2-inch  iron  bars,  and  horizontally  by  %-inch  twisted 
rods.  The  proportions  of  the  concrete  used  are :  1  Portland 
cement;  2  sharp  washed  sand;  4  crushed  limestone.  The  lin- 
ings of  both  shafts  were  built  with  great  care,  and  are  excellent 
examples  of  fireproof  shaft  construction  under  the  new  State 
law.  Below  the  concrete  the  shafts  are  limestone  except  the 
last  91  feet,  which  is  gray  shale.  The  buntons  below  the  seal 
are  placed  in  hitches  cut  in  the  rock.  The  yelloAv  pine  guides 
are  made  up  to  6  by  8  inches.  Where  the  shaft  at  a  depth  of 
100  feet  from  the  surface  passes  through  bed  7  it  is  bricked  by 
a  wall  9  feet  high  and  12  inches  thick.  The  fireproofing  of  new 
shaft  linings  now  demanded  by  a  provision  of  the  State  law  is 
now  done  in  Illinois,  but  only  a  few  shafts  have  been  sunk 
since  the  law  went  into  effect. 

HAULAGE. 

Hauling  the  coal  from  the  working  places  to  the  bottoms 


MINING  PRACTICE 


27 


y> 


Fig.    12.      Plan  and   section   of  concrete-lined   shaft. 


28 


COAL   MINING  INVESTIGATIONS 


is  beset  with  more  difficulties  in  this  district  than  in  most  Illi- 
nois mines  because  the  rolls  and  pitches  of  the  bed  make  nu- 
merous grades  as  high  as  15  per  cent.  As  the  grades  are  casual 
it  is  impossible  to  locate  the  hoisting  shaft  in  such  a  position 
that  they  shall  be  in  favor  of  the  loads;  consequently  haulage 
costs  are  higher  than  in  those  districts  where  the  bed  is  flat  or 
has  a  uniform  grade  in  favor  of  the  loads  from  rooms  to  hoist- 
ing shaft.  The  haulage  expense  is  further  augmented  by  sharp 
curves,  and  by  the  presence  of  gob  on  the  track  due  to  roof 
falls  in  sections  insufficiently  timbered. 

The  standard  electric  locomotive  is  used  for  hauling  from 
the  partings  to  the  shaft  at  5  of  the  7  mines  examined;  mules 
are  used  at  the  other  two.  Mules  gather  in  all  but  one  of 
the  mines.  In  this  one  mine  6-ton  electric  locomotives  gather 
the  loads  from  the  rooms,  running  to  the  face  for  the  pit  car  if 
the  room  lies  flat  and  pulling  the  car  out  of  the  room  by  a 
winch  called  a  "crab",  or,  in  exceptional  cases,  with  a  block- 
and-tackle  where  grades  into  the  rooms  are  steep  against  the 
loads. 


Fig.    13.      Main    entry    and    wide    pit    car. 


Steep  grades,  sharp  curves  and  gob  on  the  roadways  have 
combined  to  prevent  a  high  ton-mileage  for  locomotives.  (Ta- 
ble 11.)  The  figures  for  locomotive  ton-mileage  in  this  table 
were  computed  for  each  mine  from  the  performance  of  the 
heaviest  locomotive  when  more  than  one  operated  on  the  main 


MINING  PRACTICE 


29 


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30  COAL  MINING  INVESTIGATIONS 

haulage.  The  average  distance  in  miles  traveled  each  shift 
multiplied  by  the  average  weight  of  cars  and  coal  hauled  over 
this  distance  gives  the  locomotive's  total  ton-mileage.  The 
superiority  of  the  heavy  locomotive  is  clearly  shown.  Al- 
though the  light  locomotive  travels  a  greater  number  of  miles 
a  day,  its  daily  ton-mileage  is  low  on  account  of  inability  to 
haul  many  loaded  cars  in  a  trip. 

Entries  are  driven  so  wide  in  this  district  that  a  wide  pit 
car  can  be  hauled.  (Fig.  13.)  The  capacity  of  pit  cars  varies 
from  2100  pounds  to  8000  pounds.  The  weight  of  pit  cars  is 
in  reasonable  proportion  to  that  of  the  coal  carried,  the  weight 
of  coal  varying  from  two  to  four  times  that  of  the  empty  car. 
The  function  of  the  pit  car  is  to  act  as  carrier  of  coal,  and  any 
weight  in  excess  of  that  necessary  for  a  strong  car  increases 
the  cost  but  not  the  efficiency  of  haulage.  It  it  not  uncommon 
in  Illinois  to  find  that  50  per  cent  of  the  weight  of  the  load 
hauled  to  the  bottom  by  locomotives  or  mules  is  pit  car.  The 
per  cent  of  empty  car  weight  in  the  total  load  of  a  trip  in  this 
district  varies  from  20.0  to  46.2. 

In  Illinois  sufficient  attention  is  not  paid  to  the  running 
gear  of  pit  cars.  The  cost  of  hauling  could  be  reduced  consid- 
erably by  keeping  wheels  and  axles  in  better  condition. 

The  mules  in  this  district  are  kept  in  excellent  condition. 
The  policy  of  one  company  operating  a  number  of  mines  could 
be  advantageously  followed  throughout  the  State:  whenever  a 
mule  begins  to  show  inability  to  do  a  standard  days'  work  it 
is  taken  out  of  the  mine  and  sold.  The  average  period  of  use- 
fulness of  a  mule  in  the  mines  of  this  company  is  3  years. 
Mules  bought  for  |175  a  head  are  sold  for  |40  after  3  years 
work  underground.  It  was  impossible  to  get  figures  for  ton- 
mileage  of  mules  in  this  district.  In  the  best  managed  mines 
the  cost  of  feeding  a  mule  averages  $10  a  month  with  corn  at 
60  cents  a  hundred  and  hay  at  $15  a  ton.  For  the  working 
year  1911,  consisting  of  164  working  days,  the  cost  of  feeding 
a  mule  at  one  of  these  mines  averaged  $11.50  a  month.  At  one 
mile  with  a  2  per  cent  grade  in  favor  of  the  loads  a  spike  team 
of  3  mules  hauls  trips  of  17  cars  each  weighing  empty  1800 
pounds  and  holding  2100  pounds  of  coal,  making  a  total  weight 
of  3900  pounds  per  loaded  car  and  approximately  33  tons  for 
the  trip.  No  record  of  mules  on  grades  against  the  loads  was 
available. 


MINING  PRACTICE 


31 


Rail  weight  in  the  district  varies  from  16  to  40  pounds  on 
the  main  haulage  where  locomotives  are  used.  For  secondary 
haulage  2  mines  have  20-pound  rails  and  5  mines  16-pound 
rails.  Track  gage  varies  from  29  to  42  inches.  At  those 
mines  where  haulage  details  are  best  considered  the  ties  are 
of  sawed  white  oak  4  inches  by  6  inches  by  5  feet.  The  average 
cost  at  these  mines  is  14  cents  per  tie. 

HOISTING. 

As  the  tonnage  of  the  mines  in  this  district  is  compara- 
tively small  the  hoisting  plants  have  the  ordinary  equipment 
of  mines  with  moderate  outputs  and  small  two-compartment 
shafts.  Table  12  gives  data  on  hoisting  arrangements  at  each 
mine  examined. 

Table  12. — Hoisting 


Ho 

sting  shaft 

Hoisting  engine 

D 

rum 

6 

be 

.5 
'£ 

0 
c 

a 

<v 

.s 

Q 

Id 

M-l 
N 

C/3 

0 

en 
u 

1       C/5 

u 

■>->     <D 

5 

c 
u 

-4 

43 

Timber 

160 

14  by   12 

Yes 

18  by  32 

6 

5 

44 

Concrete 

270 

10  by  20 

Yes 

24  by  36 

6 

3^4 

45 

Timber 

320 

8  by  14 

Yes 

22  by  36 

6 

5 

46 

Timber 

450 

9  by  \y/2 

Yes 

20  by  36 

47 

Timber 

90 

7  by  4 

No 

12  by  24 

5/2 

8 

48 

Timber 

76y2 

12%  by  Sy2 

Yes 

16  by  32 

4/2 

4 

49 

Timber 

337 

9  by  1^/2 

Yes 

22  by  36 

6 

8 

The  shaft-bottoms  are  usually  loo  short  for  ample  storage 
of  loaded  cars  to  be  hoisted  and  empties  to  be  taken  inby,  but 
this  lack  of  storage  capacity  at  the  bottom  is  common  to  all 
districts  in  the  State.  One  mine  has  provided  room  for  storage, 
as  shown  in  fig.  14,  which  is  a  plan  of  the  shaft-bottom  witl? 
track  arrangements. 

Every  mine  examined  lias  self -dumping  cages.  Six  mines 
hoist  with  a  direct-connected  engine;  a  second-motion  hoist  is 
used  in  only  one  mine.  All  drums  are  cylindrical,  varying  in 
diameter  from  41/L>  to  6  feet,  and  in  length  from  W/\  to  8  feet. 
The  hoisting  engine  cylinders  are  of  comparatively  small  diam- 
eter and  short  stroke,  only  one  mine  having  an  engine  cylinder 
24  by  36  inches. 


32 


COAL  MINING  INVESTIGATIONS 


PREPARATION  OF  COAL 


In  the  smaller  mines  in  the  district  the  preparation  of  coal 
for  market  consists  only  in  passing  the  mine-run  product  over 
short  and  narrow  shaking-screens  and  in  the  district  generally, 
although   no  run-of-mine  coal   is  shipped,   little  attention   is 


Fig.   14.     Plan  of  shaft  bottom. 


given  to  cleaning  and  to  close  separation  into  sizes.    The  com- 
monest sizes  of  coal  made  are : 

Name  Size 

Lump  Over  6  inches 

Egg  Through  6  inches  and  over  3  inches 

Nut  Through  3  inches  and  over  iy2  inches 

Screenings  Through  l1/^  inches 

Table  13  gives  tipple  equipment  for  each  mine.     In  three  of 
the  mines  examined  all  coal  under  1*4  inches  is  rescreened, 


PREPARATION   OF  COAL 


33 


making  a  further  separation  of  sizes  between  3%  inches  and  l1/^- 
inches.  The  rescreener  consists  of  a  revolving  screen  5  to  6 
feet  in  diameter  and  24  feet  long,  usually  set  at  a  pitch  of  1 


Table  13.- 

—Preparation  of  coal. 

«-t-i 

Shaking 

screen 

n-. 

"rt    m 

O  jz 

0 

13*0 

O   0 

^-*    V 

c 

JH 

0  ^ 

«u 

*+H    .5 

a  t? 

•  ~  a 

Cu  <V 

0  wl75 

O 

£ 

£t5 

Inclinat 
inches 
foot 

CA    3 

|   g 

CO 

Is  c 
rescre 
or  wa 

C   1-1 
PL.    0 

43 

Wood 

14 

7 

4 

75 

Rescreened 

70 

44 

Steel 

48 

5 

3 

90 

Neither 

70 

45 

Wood 

38 

7 

4 

90 

Rescreened 

46 

Wood 

30 

8 

4 

75 

Neither 

See  foot-note  a 

47 

Wood 

38 

6 

1/5 

70 

Both 

55 

48 

Wood 

40 

6 

4 

85 

Neither 

70 

49 

Wood 

30 

6 

4 

80 

Neither 

75 

a.  45   over   3  inches. 


inch  in  4  feet,  and  making  about  20  r.  p.  m.     One  mine  washed 
its  coal  in  a  washery  of  the  Luhrig  type.    A  description  of  this 


fr-r» 

■El 


K^       -„ 


Fig.    15.      Typfca 


wasliery  is  given  in  Bulletin  09,  Coal  Washing  in  Illinois,  by 
F.  C.  Lincoln,  published  by  the  Engineering  Experiment  Sta- 
tion, University  of  Illinois: 


34 


COAL   MINING  INVESTIGATIONS 


Six  of  the  7  mines  examined  had  the  common  surface 
plants  of  frame  construction  found  at  mines  of  small  produc- 
tion. The  power  plants  of  these  6  mines  had  nothing  out  of 
the  ordinary.  Fig.  15  shows  a  typical  surface  plant  of  frame 
construction.  One  of  the  7  mines,  however,  had  a  well-arranged 
and  fire-proofed  plant  and  modern  equipment.  The  tipple  was 
of  steel  construction  and  the  boiler-house,  fan-house  and  maga- 
zine were  of  brick. 

Table  14  gives  data  on  surface  equipment  at  the  mines 
examined. 


Table  14. — Surface 

equipment 

Storage   capacity 
for  empty 
R.  R.  cars 

Boilers 

Electric 

6 

Type 

O 

H 

£    <D 

> 
< 

no 

generators 

6 

'0 
> 

43 

42 

5 

Fire  tube 

750 

150 

250 

44 

35 

4 

Fire  tube 

600 

[00 

300 

275 

45 

30 

4 

Fire  tube 

600 

no 

150 

250 

46 

40 

3 

Fire  tube 

450 

no 

100 

250 

47 

20 

3 

Fire  tube 

240 

95 

48 

24 

2 

Fire  tube 

250 

120 

150 

250 

49      J 

37 

3 

Water  tube 

450 

120 

T50 

250 

